How to create favicon-icons on Unix machines

They're from people who bookmark your website (if they're using
Internet Explorer) or if you have the following HTML code in your
HTML pages (if they have Mozilla or Konquerer).

<LINK REL="SHORTCUT ICON" HREF="http://www.mydomain.com/favicon.ico">

Making such an icon is easy if you're using Microsoft Windows (just
use PaintBrush and save it as a ICO file) and relative easy if
you're using a Unix-like operating system.

Creating an image

This part is easy, or not, depending on your graphical skills.
There are several tools available for this task. I used GIMP, it's
available from the FreeBSD ports-collection or from http://www.gimp.org.

The picture should be 16x16 pixels. Editing something that small
can be tricky, but if you zoom in up to 1600% it will be easy to
make a nice drawing.

If you save it, choose PNM format. It can be anything, but PNM will
have the least problems for the next step.

Netpbm - package of graphics manipulation programs and library

After you've made the image, it has to be transformed into the
Windows Icon format. The easiest way is to use Netpbm (available
as a port in graphics/netpbm or from http://netpbm.sourceforge.net).
If it was saved as an PNM file, the way to convert it into the
Windows Icon format is with:

ppmtowinicon -output favicon.ico <inputfile.pnm>

If you had saved it as a different format, you should convert it
from that specific format into PPM format first. For example, if
it was in the PNG or GIF format:

There are more options available in Netpbm, like rescaling (pnmscale),
cropping (pnmcrop) and rotating (pnmrotate). Very handy if you want
to run batch jobs on your pictures, like making thumnails from your
digital photos.

Adding it to your website

Now the easiest part and the one which shows of all the hard work.
Add this line to the HEAD section of your webpage:

<LINK REL="SHORTCUT ICON" HREF="http://www.mydomain.com/favicon.ico">

And reload the page. In Mozilla it shows up in the address-bar.
Netscape 4.7 doesn't support it. Konquerer does ask for them, but
I don't have it so I couldn't find out where it shows up. Opera
5.0 doesn't support it. Galeon does support them in the bookmarks
editor. Internet Explorer 5.0 does support it when you bookmark
pages.

With the release of Mozilla 0.9.7, the /favicon.ico was automaticly
fetched even if the website didn't have a link to it. With the
release of 0.9.8, this was disabled again. But you can get it back
by putting this in prefs.js:

user_pref("browser.chrome.favicons",true);

Websites running Netscape Enterprise server will have a /favicon.ico
by default, showing the Netscape Logo. So don't be surprised when you
see the familair N the address-bar.